Earlier quoted context omitted.
IIRC it's the same as doing it anywhere else. You retain someone to represent you and they do so. In some states, you must appear on your own - but not in MA, I don't think, and you can still have an attorney advising you even if they can't appear with you.
Certainly in California you must represent yourself. But you can consult an attorney. They will point out the counter-arguments that you need to be prepared for, which is a very valuable service.
I'm looking at taking two parties to small claims court, over ~$1,000 USD, and wonder if it's worth the fees to seek legal guidance.